Remove stale TODO.
Remove stale TODO.

This is no longer copy/pasted from posix_shared_memory, as we verify
seals here.

Change-Id: I73f95d24b2ec20990f4cdd4d0aa544753ef11de1
google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto